One hundred days from now, MESSENGER will execute a 15-minute maneuver that will place the spacecraft into orbit about Mercury, making it the first craft ever to do so, and initiating a one-year science campaign to understand the innermost planet. It has already been 14 years since this mission was first proposed to NASA, more than 10 years since the project officially began, and over six years since the spacecraft was launched.

A multitude of milestones have been passed on the way toward the primary science phase of the mission, including six planetary flybys and five deep-space maneuvers. This week the team has completed a milestone of a different sort: the orbital readiness review.

Today's review was the culmination of more than one year of major reviews designed to confirm the readiness of all mission elements to achieve orbit about Mercury next March and to begin orbital operations shortly thereafter.

"For this and many reviews before it we have called on a number of experts outside the MESSENGER project, from both APL and outside institutions, to review our plans to see where there are gaps or weak spots," explains MESSENGER Project Manager Peter Bedini of the Johns Hopkins University Applied Physics Laboratory. "The intent is to tap the knowledge-base of those who have lived through similar challenges, and to make any adjustments that promise to improve the chances of success in our prime mission."

"There is still work to do in preparation for orbit insertion next March, and those preparations will also be reviewed, but today's review was the last in a long series laid out more than a year ago," Bedini adds.

"MESSENGER has been on a long journey," adds MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington, "but the promised land lies ahead. All of the preparations for orbit insertion and orbital operations by the project team and the mission's many review panels have served to maximize the likelihood that the intensive exploration of the innermost planet will begin smoothly and efficiently 100 days from now."